A subsea well of the type concerned herein will have a wellhead supported on the subsea floor. One or more strings of casing will be lowered into the wellhead from the surface, each supported on a casing hanger. The casing hanger is a tubular member that is secured to the threaded upper end of the string of casing. The casing hanger lands on a landing shoulder in the wellhead, or on a previously installed casing hanger having larger diameter casing. Cement is pumped down the string of casing to flow back up the annulus around the string of casing. Afterward, a packoff is positioned between the wellhead bore and an upper portion of the casing hanger. This seals the casing hanger annulus.
Casing hanger running tools perform many functions such as running and landing casing strings, cementing strings into place, and delivering, installing, and testing packoffs. A packoff seal is often delivered to a landing position by a drop or longitudinal downward movement of the stem of a running tool. However, if the stem does not travel a sufficient distance to properly land the packoff seal, the seal may be set in an incorrect position. The consequence of an improperly set packoff seal may result in a running tool becoming stuck in a hanger, or alternatively, may require several trips to retrieve the seal, clean the area, and set another seal. Furthermore, if the running tool piston does not stroke the packoff seal sufficiently once landed, the packoff seal will not properly set.
A need exists for a technique that ensures that a packoff seal is landed in a correct position and that the packoff seal is fully set by the stroke of the piston. The following technique may solve one or more of these problems.